Chemistry Producing Hydrogen Assignment?

1. Use the mass of magnesium and temperature and atmospheric pressure to predict the volume of hydrogen of gas that would be expected to be produced by the reaction?

2. What is the experimental volume?

3. What is the percent yield of hydrogen in the experiment?

4. What are some possible reasons for this percent yield obtained? Give two reasons.

1 Answer

  • Iggy
    Lv 7
    8 years ago
    Favorite Answer

    1. The reaction I'd expect you to be performing is:

    Mg (s) + 2 HCl (aq) → MgCl2(aq) + H2(g)

    You can use the mass of magnesium to calculate the number of mole. This will be the same as the number of mole of the hydrogen (H2). Since the hydrogen is the only gas you can use the ideal gas law (as an approximation) to calculate the volume.

    PV = nRT becomes V = nRT/P where n is the number of mole of H2, R the ideal gas constant, T the room temperature at which you performed the experiment and P is the atmospheric pressure.

    2. Is based on what you measured during your practical session. It is a number you should have recorded.

    3. The percent yield is the ratio of experimental vs predicted volume expressed as a percentage.

    4. Makes sense only with the above (you didn't supply your experimental results). I would assume a yield of slightly less than 100% because of incomplete reaction, side reactions, impurities in the magnesium, etc. If you get higher yield this could only be because of some other reaction due to impurity.

    Enjoy :)

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